The present invention is directed to a method and device for heating water, e.g., for household use, and for concurrently providing distilled water, e.g., for drinking (a thermostil). In the device, the energy used to distill water is then used to heat water in, say, a water heater, thus providing a very economical technique for obtaining clean drinking water. Currently, the cost of distilled water for drinking purposes or other forms of human consumption is uneconomical.
Some techniques or apparatuses have been proposed for economical drinking water distillation. One apparatus includes a water heater and distiller apparatus in which condensing steam in the distilling portion of the apparatus gives up its latent heat to water which is being heated in the water heating portion of the apparatus. However, the devices promote the use of separate or auxiliary heating elements and controlling energizing thereof based on an amount of fluid in a boiler, rather than exploiting the constant source of energy provided by a pilot light and controlling the amount of fluid to be evaporated thereby according to the amount of fluid in the boiler or amount of fluid recovered in a distillate tank. See, for example, U.S. Pat. No. 4,690,102, issued Sep. 1, 1987, to G. Sundquist, for Water Heater and Distiller Apparatus and U.S. Pat. No. 5,304,286, issued Apr. 19, 1994, to D. G. Palmer, entitled Water Supply System. 
Another device includes a feed water intake which provides water in excess of the distilled water output, a heater controlling the quantity of water boiled, a waste water exit port to remove accumulated water above a certain level, a distilled water exit port in the vapor space, a condensing device to transfer the heat of condensation to a hot water tank and a waste water heat exchange device to transfer heat from a waste water to the hot water tank. See, for example, U.S. Pat. No. 4,601,789, issued Jul. 22, 1986, to J. G. Bjorklund entitled Water Purification Apparatus. 
What are needed, and not taught or suggested in the art, are an apparatus for and a method of heating fluid with a gas heater and distilling fluid with the pilot light of the gas heater, and an apparatus for heating fluid with a gas heater and distilling fluid with an electric filament.